The present invention relates to an automatic bending machine for the production of multi-form small parts from a metal band or wire, comprising supporting frame means, a central toothed driving wheel mounted in said frame means for rotation about a main axis, a plurality of slide units arranged on said frame means around a central working station, a plurality of bending tools, each one connected with one of the slide units, a plurality of driving devices for reciprocating the respective slide units, a driving shaft mounted for rotation in a housing of each of said driving devices about an axis which is parallel to the main axis, the driving shaft protruding from said housing into said frame means, a pinion fastened at the protruding end of each of said driving shafts and being in engagement with said toothed central wheel.
According to the state of art the driving shaft is provided with a cam plate. A small idle pulley is rotatably mounted on a shaft fixed on the slide unit. By means of a return spring the idle pulley is held in contact with the circumference of the cam plate. Such driving mechanisms have been used in the past in large numbers and operate satisfactory in slow-speed bending machines. However when the operating speed is increased wear at the idle pulley will occur already after a short time. The result is that the bending operations no longer can be precisely performed and when handling precise work pieces waste will be produced.
Therefore one object of the invention is to improve the driving device of the bending machine so that it can be used in connection with high-speed bending machines.
One further object is to provide a new driving device which allows a higher stroke number per minute without any troubles and for a long lifetime.
Another object of the invention is to provide a new driving system avoiding separate driving elements for the work stroke and the return stroke.
One further object is to replace the known cam-follower-arrangement by a completely sealed other system using an oil filling for lubricating the moving parts.